Motor fuel and lubricating oil compositions



United States Patent Office 3,11%??? Patented Jan. 28, 1964 This invention relates principally to novel motor fuel compositions containing additives which are effective in suppressing surface ignition and other deleterious depositinduced phenomena in spark-ignition internal combustion engines operating on fuels containing organo-lead compounds as additives.

Surface ignition is the ignition of engine fuel, at times other than by normal spark initiation, by glowing or burning carbonaceous material which is deposited on engine combustion chamber surfaces. These carbonaceous deposits are principally derived from the decomposition of the fuel and/ or lubricant used in the engine. Also contained in the engine deposits are products resulting from the decomposition of fuel and/ or lubricant additives. The presence, in engine deposits, of decomposition products of organo-lead compounds such as, particularly, tetraethyl lead and other tetra-alkyl lead antiknock compounds is especially deleterious, since these products appear to catalyze ignition of carbonaceaus decomposition products at relatively low temperatures, thereby greatly increasing surface ignition in an engine. Surface ignition is deleterious in that it causes loss of power and an increase in the fuel octane requirement of the engine for knock-free performance. The audible indications of surface ignition, such as wild ping and rumble, are also undesirable in that they cause considerable annoyance and concern to the engine operator.

It has now been discovered that members of a limited class of alkyl esters of unsubstituted or alkyl-substituted cyanoacetic and dicyanoacetic acids are markedly effective in suppressing surface ignition and other deposit induced phenomena when such compounds are introduced in small but sufficient amounts into the combustion chambers of a spark-ignition internal combustion engine operating on a fuel containing an organo-lead compound as an additive. Compounds suitable for the practice of this invention satisfy the generic, empirical formula wherein R is hydrogen or an alkyl group having from 1 to about 12 carbon atoms, inclusive, R is an alkyl group having from 1 to about 12 carbon atoms, inclusive, and X is hydrogen or a second cyano group (CN). The alkyl groups can be straightor branched-chain. It is essential that the one or two permissible cyano groups be appended to the carbon atom which is located alpha to the carboxy group of the acid from which the esters of the invention are derived. Illustrative but non-limiting specific examples of suitable compounds include: methyl cyanoacetate, n-butyl cyanoacetate, sec-butyl cyanoacetate, iso-butyl cyanoacetate, tort-butyl cyanoacetate, n-octyl cyanoacetate, 2-ethylhexyl cyanoacetate, n-dodecyl cyanoacetate, methyl dicyanoacetate, 3-rnethylbutyl dicyanoacetate, n-heptyl dicyanoacetate, 2,2,4-trimethylpentyl dicyanoacetate, n-nonyl dicyanoacetate, nundecyl dicyanoacetate, methyl ot-cyanopropionate, ethyl a,u-dicyanobutyrate, propyl a-cyanocaproate, tert-butyl a,a-dicyanocaprylate, n-hexyl :x-cyanoisobutyrate, n-decyl a,a-dicyanolaurate and the like; Compounds suitable for use in the practice of this invention are commerciallyavailable, or they can be conveniently prepared by conventional methods which are well known.

The use of methyl cyanoacetate in the practice of this invention is particularly preferred. This compound is commercially available and is a colorless liquid having at specific gravity of 1.1225 (15 C./4 C.), an atmospheric boiling point of 203 C., and a melting point of -22.5 C. It is represented by the empirical formula ll NC CHaC-OCH3 As stated above, in order to achieve the benefits of this invention it is necessary only to introduce a small but sufficient amount of a suitable compound into the combustion chambers of an operating internal combustion engine. This may be accomplished, for example, by incorporating the compound into the motor fuel and/or crankcase lubricating compositions, as an additive therein, or by injecting the compound directly into the combustion chambers through an aperture such as the air and/ or fuel intake systems. Generally, it will be most convenient and beneficial to introduce the compound into the combustion chambers as an additive in the motor fuel composition, and the following detailed description of the practice of this invention will, in general, be limited to this preferred embodiment.

The novel gasoline compositions of the invention comprise mainly petroleum hydrocarbons boiling in the gaso line range of from about F. to about 440 F. at atmospheric pressure, and usually from about F. to about 400 F. Both automotive gasoline and aviation gasoline are within the scope of this invention. Aviation gasoline has a more closely specified atmospheric boiling range, generally extending from a minimum of about F. to a maximum of about 350 F.

The gasoline compositions of the invention also contain an anti-knock amount of an organo-lead anti-knock compound. Tetraethyl lead (TEL) is the most commonly used organo-lead anti-knock compound, although other tetra-alkyl lead and aryl-substituted organo-lead compounds such as tetramethyl lead, tetraphenyl lead, tetraisopropyl lead, triethyl methyl lead, diethyl dimethyl lead, and tetra-amyl lead are sometimes used. Physical and equilibrium product mixtures of these compounds can also be employed. In automotive gasoline the organolead anti-knock compounds are used in amounts ranging from about 0.5 to about 4.0 cc. of the compound per gallon of gasoline, while in aviation gasolines a greater amount can be used, viz., up to about 6.0 cc. per gallon.

Along with the organo-lead anti-knock compound, various volatile halohydrocarbons are normally incorporated in the gasoline in lead scavenging amounts, i.e., in amounts theoretically calculated to convert the lead in the organo-lead compound to volatile compounds, viz., to lead dihalides. Examples of such halohydrocarbon lead scavengers are: organo-bromides and -chlorides such as ethylene dibromide, ethylene dichloride, acetylene tetrabromide, hexachloropropylene and mixtures thereof; monoand poly-halopropanes, -butanes and -pentanes; polyhaloalkyl benzenes; and mixtures thereof with each other and the like. It is therefore to be clearly understood that the novel additives of this invention can be used in leaded gasoline compositions either with or with out all such lead scavengers as are commonly employed, and in such amounts as may be required. The phrase organo-lead anti-knock agentis thus intended to include such lead scavengers.

It is also to be understood that all other gasoline additives commonly employed in the art such as, for example, other anti-knock agents (e.g., cyclomatic manganese tricarbonyl anti-knock compounds), adjuvants for the antiknock agents (e.g., tertiary butyl acetate for the tetra- 3 alkyl lead anti-knock agents), anti-icing agents, scavengers, detergents, corrosion-inhibitors, stabilizers, dyes and the like can also be employed in the novel gasoline compositions of the invention in addition to the organo-lead antiknock compound and the alkyl ester of the cyano-acid.

The additive of the invention is incorporated in the gasoline composition containing the organo-lead antiknock compound in a very small amount, which is sufficient to suppress the tendency of the engine deposits to cause surface ignition and other undesirable deposit- Iinduced phenomena during subsequent engine operation. Generally, amounts of the additive material in the range 'of from about 0.05% to about 2.0% by volume of the :resulting gasoline compositions, and preferably from about 0.1% to about 1.0%, give good results. The amount employed in a particular instance will normally depend upon the amount of organo-lead anti-itnock compound also present in the fuel composition. On occasion however, concentrations above or below the aboverecited ranges can be used.

Where a compound suitable for use in accordance with this invention is introduced into the combustion chambers of the engine as an additive in the crankcase lubricating composition, substantially greater concentrations of the additive than recited above for motor fuel compositions will be required. This is for the reason that, normally, only a relatively small amount of the lubricating composition manages to leak past the piston rings and enter into the combustion chambers. Generally, concentrations of the additive greater than 5.0% by volume will be required for the practice of this embodiment, but usually not in excess of about 15.0% by volume. Suitable amounts in any instance can readily be determined by a few simple experiments. All types of base lubricating compositions are suitable for introducing the additive into the combustion chambers, including petroleumderived, mineral lubricating oils and synthetic lubricating compositions.

The compounds employed as additives in motor fuels or crankcase lubricating compositions in accordance with this invention are not all soluble in petroleum hydrocarbons in the concentration ranges disclosed. Generally, the lower molecular weight compounds, i.e., those wherein the ester and/or substituent alkyl groups contain relatively few carbon atoms, will be insoluble in petroleum hydrocarbons in the recited ranges, and the use of mutual solvents or dispersants will be required. Classes of compounds suitable for use as mutual solvents or dispersants include the loWer-molecular-Weight, saturated aliphatic alcohols, ethers and other polar compounds. Methanol is especially suitable as a mutual solvent or dispersant, and can be used in any amount required by the nature of the fuel composition. Aromatic amines such as toluidine and amine derivatives such as the nitrosamines can also be so used. Generally, also, the higher molecular weight additives of this invention will not require the use of mutual solvents or dispersants for their stable incorporation into petroleum hydrocarbon fractions in the contemplated concentrations.

In order to illustrate a specific embodiments of this invention, commercially-available methyl cyanoacetate is incorporated in one of three portions of a leaded, com- ;mercial, high-octane automotive gasoline in a small amount which is equivalent to 0.53% by volume of the resulting gasoline composition. Methanol in a concentration of 3.4% by volume of the resulting fuel is employed as a mutual solvent or dispersant. The commercial gasoline employed contains 3 cc. per gallon of tetraethyl lead compound, and also the customary accompanying amount of halohydrocarbon lead scavengers. The resulting composition illustrates the novel motor fuels of this invention.

To one of the two remaining portions of the leaded base gasoline, methanol is added in an amount equivalent to 3.4% by volume of the resulting fuel- This motor fuel composition is used to demonstrate that methanol, without the additive of the invention, is of little benefit in suppressing surface ignition and other undesirable deposit-induced phenomena. The third portion of the leaded base gasoline is used, as is, as a control sample.

The elfectiveness of the additives of this invention is demonstrated in a conventional, spark-ignition, internal combustion engine, having a compression ratio of 12:1, and employing a commercially-available, high-compression SAE 10W30 petroleum lubricating oil. Prior to each test operation, the internal parts of this engine comprising the cylinders, pistons, rings, valves and combustion chambers are thoroughly cleaned so as to remove previously-accumulated engine deposits. The engine is also equipped with new spark plugs and piston rings prior to each test operation.

The engine is first operated on the control portion of the loaded base gasoline, which contains neither the additive material of the invention nor methanol, for a period of time sufficient to build up an equilibrium quantity of representative engine deposits. The tendency of these deposits to promote audible surface-ignition phenomena is then determined by a test procedure which is termed the leaded iso-octane-oenzene test or, more simply, the LLB. Test. This test involves operating the engine, containing the equilibrium engine deposits as above produced, on individual members of a series of standard reference fuels which are mixtures of leaded (3.0 cc. of tctraethyl lead per gallon) iso-octane and benzene in different proportions. Each such reference fuel is individually identified by a number, termed the LLB. number, which is numerically equal to the volumetric proportion of isooctane in that particular leaded iso-octane and benzene blend. Pure leaded iso-octane, with an L.I.B. number of 100, exhibits the greatest resistance to deposit-induced surface-ignition, while pure leaded benzene, with an L.I.B. number of 0, exhibits the least resistance. The lowestnumbered reference fuel which permits the engine to operate with only barely audible surface-ignition is termed the LLB. rating of the accumulated engine deposits. The lower the LIB. rating, the less prone are the deposits to cause surface-ignition phenomena.

The equilibrium engine deposits resulting from operation of the engine on the leaded base asoline without either the additive material of the invention or methanol are found by the above procedure to have an L.I.B. rating of 62.

After carrying out a procedure identical to that described above, involving reconditioning the engine and operating it for a period of time sufficient to accumulate an equilibrium quantity of engine deposits, it is determined by the L.I.B. technique that the engine deposits re sulting from comparable operation of the engine on the leaded base gasoline containing only 3.4% by volume of methanol have an L.I.B. rating of 58. This rating is only 4 LLB. numbers bel w that of the base gasoline alone, and does not represent a very significant improvement.

The engine is then overhauled, as before, and is operated on the motor fuel composition of this invention which contains 0.53% by volume of methyl cyanoacetate in addition to 3.4% by volume of methanol. After comparable operation for a period of time sutlicient to accumulate an equilibrium quantity of representative engine deposits, the accumulated deposits are rated in accordance with the LLB. technique, and are found to have an LLB. rating of only 23. The latter number represents a very significant reduction in the surface-ignition-promoting tendencies of the engine deposits from the leaded base fuel.

It is evident from the above that the use of the motor fuel compositions of this invention results in a significant reduction in the tendency of engine deposits derived from the base gasoline to cause surface ignition. When other embodiments of the invention are practiced as herein described, such as the employment of a crankcase lubricating composition within the scope of the invention, substantially equivalent results are obtained.

The invention claimed is:

1. Motor fuel composition consisting essentially of: petroleum hydrocarbons boiling within the gasoline range; an anti-knock amount of an organo-lead anti-knock agent; and a small amount, sufficient to suppress engine surface ignition, of a compound having the formula wherein R is selected from the group consisting of hydrogen and an alkyl group containing from 1 to 12 carbon atoms, R is an alkyl group containing from 1 to 12 carbon atoms and X is selected from the group consisting of hydrogen and a cyano group.

2. Composition according to claim 1 wherein the se lected compound is methyl cyanoacetate.

3. Composition according to claim 2 wherein the organo-lead anti-knock compound in said organo-lead antiknock agent is tetraethyl lead.

4. Crankcase lubricating composition for spark-ignition internal combustion engines consisting essentially of:

a crankcase lubricating oil; and a small amount, sufiicient to suppress engine surface ignition, of a compound having the formula realms wherein R is selected from the group consisting of hydrogen and an alkyl group containing from 1 to 12 carbon atoms, R is an alkyl group containing from 1 to 12 carbon atoms and X is selected from the group consisting of hydrogen and a cyano group.

5. Composition according to claim 4 wherein said crankcase lubricating oil is a crankcase lubricating fraction of petroleum hydrocarbons.

6. Composition according to claim 4 wherein the selected compound is methyl cyanoacetate.

References Cited in the file of this patent UNITED STATES PATENTS 2,228,662 Holm May 31, 1939 2,553,065 Somogyi Mar. 17, 1949 2,665,526 Cope Oct. 13, 1953 2,993,773 Stromberg July 25, 1961 

4. CRANKCASE LUBRICATING COMPOSITION FOR SPARK-IGNITION INTERNAL COMBUSTION ENGINES CONSISTING ESSENTIALLY OF: A CRANKCASE LUBRICATING OIL; AND A SMALL AMOUNT, SUFFICIENT TO SUPPRESS ENGINE SURFACE IGNITION, OF A COMPOUND HAVING THE FORMULA 